研究目的
To compare simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through antiferromagnetic phase transitions in Mn3Sn, investigating differences in transition temperatures and switching fields between bulk and surface properties.
研究成果
Simultaneous MOKE and AHE measurements reveal unexpected differences in transition temperatures (T1 and TN) and coercive fields between surface and bulk of Mn3Sn, indicating distinct magnetic properties. This suggests that surface and bulk undergo phase transitions at different conditions, which is significant for applications in non-collinear antiferromagnets and calls for further investigation into the underlying mechanisms.
研究不足
The study is limited to Mn3Sn crystals with specific stoichiometry (slightly Mn-deficient). Surface effects such as oxidation or strain from polishing may influence results, but were tested and found not to be the primary cause. The penetration depth of MOKE (~20 nm) might not fully capture very surface-specific phenomena, and differences could be due to intrinsic surface-bulk disparities not fully understood.
1：Experimental Design and Method Selection:
The study involves simultaneous measurements of AHE and MOKE to probe magnetic phase transitions in Mn3Sn. AHE is used to sense bulk magnetic properties via electrical means, while MOKE is used for surface-sensitive optical probing. Magnetic fields are applied in-plane, and temperature is controlled to observe transitions.
2：Sample Selection and Data Sources:
Slightly Mn-deficient Mn2.97Sn1.03 crystals grown by the molten metal self-flux method are used. Samples are cut and polished to a mirror finish on the (0001) surface, confirmed by Laue diffraction.
3：97Sn03 crystals grown by the molten metal self-flux method are used. Samples are cut and polished to a mirror finish on the (0001) surface, confirmed by Laue diffraction.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment includes an electromagnet for applying magnetic fields, a temperature-controlled stage with 100 mK stability, Pt wires for electrical contacts, a 632.8 nm laser for MOKE, balanced photodiodes for Kerr rotation measurement, and lock-in techniques for AHE measurements. Materials include Mn3Sn crystals and polishing paper.
4：8 nm laser for MOKE, balanced photodiodes for Kerr rotation measurement, and lock-in techniques for AHE measurements. Materials include Mn3Sn crystals and polishing paper.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Samples are mounted, and simultaneous MOKE and AHE measurements are performed in a dry air environment. Magnetic fields are swept, and temperature is ramped to observe hysteresis and phase transitions. Data is collected continuously during temperature changes.
5：Data Analysis Methods:
Hysteresis loop amplitudes (DhK and DqH) are analyzed to determine transition temperatures and coercive fields. Statistical analysis includes histograms of coercive fields from multiple surface locations.
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